1. Field of the Invention
The present invention relates to a flexible electro-heating apparatus and fabrication method thereof. Moreover, in particular, the electro-heating apparatus according to the invention includes a fabric-type heating device. In daily life, the electro-heating apparatus of the invention can be implemented as various articles providing heat, such as garments for keeping warm, electric blankets, window curtains for isolating cold air, cushions for melting snow, repair kits for repairing tires, etc.
2. Description of the Prior Art
With the development of material science and engineering, various kinds of fabrics with heating function are developed. The prior arts of these fabrics are described as follows.
The first type of fabrics with heating function uses heating devices that are mainly formed of traditional heating coils or heating flakes, combining with typical fabrics. It is necessary to stress that the characteristics of the first type of fabrics with heating function are merely to use textile fabric to wrap up traditional heating-coils or heating flakes. The related prior arts of the above-mentioned type are listed as follows: U.S. Pat. Nos. 6,160,246; 6,111,233; 5,792,714; and Taiwan Utility Model Patent Nos. 135,293; 282,662; and 117,353.
The first type of fabrics with beating function have many problems mainly caused by adopting heavy heating coils or beating flakes, e.g., limited heating efficiency, limited applications, lack of safety measures.
The second type of fabric with heating function uses endothermic/exothermic particles of phase change materials that are coated on the textile fabric, and thus the type of fabric is able to adjust temperature by the endothermic/exothermic property of the phase change materials. The related prior arts of the second type of fabrics with heating function are listed as follows: the U.S. Pat. Nos. 5,885,475 and 6,207,738. Comparing with the first type of fabric with heating function, the second type of fabric with heating function can be made into flexible fabric with beating function.
However, the endothermic/exothermic property of the phase change material used by the second type of fabric with heating function, is limited The adjustable temperature range of the second type of fabric with heating function is very narrow, and about ±2° C. Besides, wearers are unable to control the temperature provided by the second type of fabric with heating function. Therefore, the real efficiency of the textile fabric, coated with particles of phase change materials all over, is merely for keeping wearer comfortable, but not for keeping wearer warm. Besides, the cost of the second type of textile fabric with phase change material is expensive. Even though the second type of fabric with heating function is washable, its washing frequency is limited owing to limitation of used phase change materials.
To form the third type of fabric with heating function, first, metal fibers are twirled into conductive yarns, and then the conductive yarns directly combine with a soft matrix (ex. weave cloth) as the third type of fabric by textile technology. The conductive yarns also make conductive circuits of the fabric with heating function to replace heating coils used in traditional heating apparatus. The above-mentioned conductive yarns, which combine with the soft matrix and make conductive circuits, must be connected to a power supply, and transfer electric energy supplied by the power supply into heat. Obviously, the third type of fabric with heating function can be made into flexible electro-heating apparatus. The third type of fabric with heating function can further combine with, a temperature sensor and a temperature controller to provide users with the function of controlling temperature. The related prior arts of the fabrics with heating function using heaters made of conductive yarns are listed as follows: the U.S. Pat. No. 6,548,789 and the U.S. Pat. No. 6,545,253.
The third type of fabric with heating function overcomes those drawbacks of traditional electro-heating apparatuses, such as heaviness of metal coils, inconvenience to wash, etc. Therefore, the third type of fabric with heating function can be extensively put into practice for keeping warm or for isolating cold air, e.g., garments for keeping warm, electric blankets, hot compress cushions, scat cushion for keeping warm, and window curtains for isolating cold air, etc.
However, the third type of fabric with heating function still has an obvious drawback, that is, only the areas of the fabric covered by conductive yarns can provide heat because the heat is transferred from electric energy by circuit loop formed of the conductive yarns. More exactly, this type of fabric is a one-dimensional electro-heating apparatus, meaning that the zone covered by heat source is substantially a one-dimensional, zone. Therefore, the temperature distribution generated by this type of heating fabric is not uniform. Besides, even, though the application of the third type of fabric with heating function is extensive, this type of fabric cannot be used under the environment in which higher heating power is needed for unit areas, such as the environment in which over 1000 W/m2 heating power is needed for unit areas.